1. Field of the Invention
The present invention relates to a differential signal transmission cable having a structure in which a shield tape is longitudinally wrapped, and a multi-core cable.
2. Description of the Related Art
Hitherto, a differential signal transmission cable is known in which an insulator is provided around a pair of center conductors to transmit a differential signal, and a shield tape including an insulator layer having one surface provided with a conductor layer is wrapped around the insulator.
In the differential signal transmission cable as stated above, when the shield tape is spirally wrapped around the insulator, the insulator layer and the conductor layer are periodically arranged along the longitudinal direction of the cable. Thus, there is a problem that a resonant phenomenon (suck out) occurs due to the wrapping pitch of the shield tape, and a usable frequency band is limited. In order to avoid such a problem, a differential signal transmission cable is proposed in which a shield tape is longitudinally wrapped around an insulator such that both ends of the shield tape overlap each other along the longitudinal direction of the cable.
In the differential signal transmission cable including the shield tape longitudinally wrapped, a unit configured to closely wrap the shield tape around the insulator and to prevent loosening of the shield tape is required.
U.S. Pat. No. 7,790,981 (Patent Literature 1) discloses a differential signal transmission cable having a structure in which an insulating tape for pressing is laterally wrapped (spirally wrapped) around a shield tape. In Patent Literature 1, a first insulating tape is spirally wrapped around the shield tape so that an adhesive surface faces outside, and further, a second insulating tape is spirally wrapped around the outside thereof so that an adhesive surface faces inside and wrapping directions of both the insulating tapes are opposite to each other. The adhesive surfaces of the two insulating tapes are adhered to each other and fixed, and the loosening of the shield tape is prevented.
U.S. Pat. No. 6,677,518 (Patent Literature 2) discloses a differential signal transmission cable in which an insulating material is covered, as a sheath, on the outside of a shield tape.